1. Field of the Invention
The present invention relates to an optical apparatus such as an image sensor unit, a lens barrel unit, a lens integrated camera, and a microscope.
2. Description of the Related Art
Recently, optical apparatuses such as a digital video camera and a digital still camera have been increasingly required to be downsized. For example, a so-called inner focus zoom type is smaller than a front focus type because a front lens and an image sensor are fixed while a magnification-varying unit and a focus unit are made movable in an optical axis direction inside a lens barrel. A retractable lens barrel is also smaller because the image sensor is fixed while the magnification-varying unit including the front lens is moved in the optical axis direction. However, a heating value of the image sensor generates tends to increase due to an increasing number of pixels, and a heat radiating measure becomes necessary.
Japanese Patent No. 4194221 discloses a retractable lens barrel configured to move a front lens in varying the magnification. Japanese Patent Laid-open No. 2010-56995 discloses a camera including a Peltier element for heat radiations of an image sensor.
The structure of Japanese Patent No. 4194221, in which a first lens unit optical system has the front lens is made of a large glass and hence is heavy, is disadvantageous for quick zooming and smooth moving-image capturing. In addition, a smaller F-number leads to a larger optical system, and requires a large complicated drive mechanism. It is difficult to mount the structure of Japanese Patent Laid-open No. 2010-56995 in a small camera, because the Peltier element and heat transfer structure are too complicated.